U.S. patent number 4,005,883 [Application Number 05/600,941] was granted by the patent office on 1977-02-01 for tube couplings.
Invention is credited to John Derek Guest.
United States Patent |
4,005,883 |
Guest |
February 1, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Tube couplings
Abstract
A tube coupling comprises a collet with resilient arms arranged
to co-operate with a cam surface of a surrounding body or sleeve,
the cam surface tapering in the axial direction such that, as a
tube in the collet is pulled outwardly, frictional pull between the
tube and collet causes the collet to move in a direction to tighten
the grip on the tube. The arms of the collet are spaced apart
radially such that, in the absence of any tube, the collet can be
withdrawn outwardly from the sleeve or body. Pushing the collet
inwardly into the sleeve or body allows the arms to move radially
outwardly and then the tube can be withdrawn. The collet has a
flange or the like extending radially outside the sleeve or body
and a spring clip is provided between this flange and the sleeve or
body to lock the coupling against release of the tube. By using
such a clip holding the collet outwardly of the body, the arms of
the collet are retained in a position gripping the tube; the clip
prevents the collet from being pushed inwardly to release the
tube.
Inventors: |
Guest; John Derek (Bray,
Maidenhead, Berkshire, EN) |
Family
ID: |
10364260 |
Appl.
No.: |
05/600,941 |
Filed: |
August 1, 1975 |
Foreign Application Priority Data
|
|
|
|
|
Aug 5, 1974 [UK] |
|
|
34327/74 |
|
Current U.S.
Class: |
285/322;
285/369 |
Current CPC
Class: |
F16L
37/0845 (20130101); F16L 37/0925 (20130101) |
Current International
Class: |
F16L
37/092 (20060101); F16L 37/00 (20060101); F16L
021/06 () |
Field of
Search: |
;285/321,322,323,113,35,156 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Larkin; G. V.
Attorney, Agent or Firm: Graybeal, Barnard & Uhlir
Claims
I claim:
1. In a tube coupling of the kind having a collet comprising a
cylindrical portion with a cylindrical base and with resilient arms
arranged to cooperate with a cam surface which cam surface is
extending axially from one end of said cylindrical portion
constituted by a member surrounding the collet and having an
internal surface tapering to a smaller diameter in one axial
direction engaging the arms so that the arms are forced inwardly by
axial movement of the collet in said one direction, the improvement
wherein the arms have, near their outer ends, radially inwardly
extending projections which, when the aforesaid cam surface and
tapered surfaces are engaged to force the arms inwardly, extend
radially inwardly to positions nearer the axis of the collet than
the surface defined by said cylindrical bore, and when the arms of
the collet are spaced apart in the circumferential direction such
that, in the absence of any tube within the collet, the arms can
move inwardly to permit of the collet being withdrawn from said
member by axial movement in said one direction and wherein said
member has a shoulder facing the ends of the arms of the collet,
the shoulder defining a bore of smaller diameter than the bore
through the collet.
2. A tube coupling as claimed in claim 1 and comprising a unitary
body member incorporating said cam surface together with a collet
and an O-ring elastomeric seal retained in the body member by the
collet.
3. A tube coupling as claimed in claim 1 wherein the collet,
outside said member, extends radially outwardly to be larger than
the bore in said member forming the cam surface.
4. A tube coupling as claimed in claim 3 wherein the collet has a
radially extending flange at its outer end.
5. A tube coupling as claimed in claim 4 and having a removable
clip around the collet between the flange and said member for
preventing movement of the collet into said member and thereby
preventing radially outward movement of said arms, whereby said
clip enables a tube to be secured against removal from the
collet.
6. A tube coupling as claimed in claim 5 wherein said clip is a
spring clip.
7. A tube coupling comprising an outer member having an internal
bore, a collet fitting in said bore from one end thereof and a seal
seated within said bore against a shoulder therein which shoulder
faces the end from which the collet is inserted, the bore in said
member, between the shoulder and the end from which the collet is
inserted having a tapered section tapering from the larger diameter
part enclosing the seal down to a smaller diameter portion within
which the collet is slidable, and the collet including a portion of
externally cylindrical form slidable in the reduced diameter
portion of said bore, from which externally cylindrical portion
there extends, in an axial direction, three or more resilient arms
for gripping a tube, said arms having, on their outer faces,
surface portions for engaging the tapered part of said bore, said
collet furthermore having a cylindrical bore with inwardly
extending projections at the ends of said arms remote from the
cylindrical portion of the collet which inwardly extending portions
have a sloping face on the surface of those portions facing towards
the outer end of the collet and bore, and the inwardly extending
projections on the collet arms being of such dimensions compared
with the diameter of the enlarged portion of the bore and the outer
surface of the collet arms that, when the collet is adjacent the
seal, a tube can be forced through the collet to bear against the
inwardly extending projections and force the collet arms apart so
that the tube passes through the collet and the seal to be
resiliently gripped by the collet.
8. A tube coupling as claimed in claim 7 wherein said seal is an
O-ring seal.
9. A tube coupling as claimed in claim 7 and for coupling two tubes
together wherein said member is constituted by a single sleeve with
a separate collet and O-ring inserted from each end.
10. A tube coupling as claimed in claim 7 wherein the bore in said
member, beyond the seal, has a cylindrical portion of suitable
diameter to be a close fit on the tube, this cylindrical portion
terminating in a shoulder forming an abutment for the end of the
tube.
11. A tube coupling as claimed in claim 10 wherein, to facilitate
insertion of the collet into the bore, the mouth of the bore has a
tapered surface and the ends of the collet arms have
correspondingly sloped surfaces for engaging the tapered mouth so
that the collet arms are gradually forced inwardly as they enter
the mouth of the bore.
12. A tube coupling as claimed in claim 7 wherein the collet has a
flange at its outer end.
13. A tube coupling as claimed in claim 1 and having an elastomeric
bush around the tube within the collet.
14. A tube coupling as claimed in claim 7 wherein said bore has a
second shoulder located between the smaller diameter end of the
tapered section and said smaller diameter portion of the bore and
facing in the opposite direction to the first mentioned shoulder
and wherein said arms have outwardly extending portions at the ends
of said arms remote from the cylindrical portion of the collet to
form abutment surfaces limiting axial movement of the collet in
said bore by engaging said second shoulder.
15. A tube coupling of the kind having a collet and a body portion,
said collet comprising a cylindrical portion with a cylindrical
bore and resilient arms extending axially from said cylindrical
portion, said body portion having a bore open at one end and in
which said cylindrical portion of the collet is slidable, said bore
in the body portion remote from the open end having an enlarged
portion having as internal surface forming a cam surface, said
internal surface tapering to a smaller diameter in the axial
direction towards the open end of the bore, which tapered surface
engages said arms so that the arms are forced inwardly by axial
movement of the collet towards the open end of the bore in the body
portion, the collet having its arms spaced apart in the
circumferential direction such that, in the absence of any tube
within the collet, the arms can be moved inwardly to lie partially
within a cylinder of the diameter defined by the bore in the body
portion and wholly with a cylinder of the diameter defined by said
cylindrical portion of the collet, whereby the collet is insertable
in the bore from the open end thereof and whereby axial movement of
the collet, by engagement of the arms with said tapered surface
enables the arms to be forced inwardly of the minimum diameter of
the collet for gripping a tube inserted therein, and wherein said
bore in the body portion has, beyond said tapered surface, a part
of smaller diameter than the cylindrical bore in said collet.
16. A tube coupling as claimed in claim 15 wherein said arms have
radially outwardly extending portions at the ends of the arms
remote from the cylindrical portion of the collet and wherein said
bore in said body portion has a shoulder located between the
smaller diameter end of the tapered surface and the open end of the
bore in the body portion, said shoulder facing away from said open
end of the bore, said shoulder and said outwardly extending
portions on said arms forming complementary abutment surfaces to
limit axially outward movement of the collet.
17. A tube coupling as claimed in claim 15 and having a bush of
elastomeric material located axially of the bore of the collet
within the arms of the collet.
18. A tube coupling as claimed in claim 17 wherein the collet is
formed of metal strips of uniform thickness.
Description
BACKGROUND OF THE INVENTION
This invention relates to couplings for tubes.
The invention is more particularly concerned with a tube coupling
of the kind having a collet with resilient arms arranged to
co-operate with a cam surface on a member surrounding the collet,
which member has an internal surface tapering in one axial
direction and engaging the arms of the collet so that the fingers
are forced inwardly by axial movement of the collet in one
direction. With such a tube coupling, the end of the tube may be
pushed into the coupling through the collet from the end thereof
remote from the arms. Any outward pull on the tube with respect to
said member surrounding the collet tends, by the engagement between
the collet and the tube, to pull the collet in the direction to
remove it from said member and thereby causes the arms, by
engagement with the cam surface, to grip the tube more tightly.
Provided the coupling is of the appropriate size to fit the tube,
if a tube is inserted in the collet, the inward movement of the
arms is restricted and hence the collet cannot be withdrawn
outwardly from said member. This arrangement thus gives a form of
coupling in which the end of the tube can be inserted directly into
the coupling and is engaged thereby in a manner which prevents
withdrawal of the tube merely by any pull thereon. The tube can be
released however by pushing the collet inwardly into said member
whilst pulling the tube outwardly; thus release can only be
effected by a deliberate action and not by accidental pull on the
tube.
It is an object of the present invention to provide an improved
form of tube coupling of this kind. In considering the problems
with prior types of constructions, it is convenient to refer to the
end of the collet having the arms as the inner end and the other
end of the collet as the outer end; the arms thus extend from a
point along the length of the collet towards the inner end. In
prior types of coupling, the taper on the cam surface, which taper
is such that the diameter reduces from the inner end towards the
outer end, has necessitated that the collet should be inserted into
the member forming the cam surface from the inner end of that
memer. This then leads to the requirement that the main body of the
coupling must be formed in two parts so as to permit the assembly
of the collet into a part having the required cam surface and then
the securing of this member into a main part of the body. Also,
since the collet has to be assembled into the member with the cam
surface from the inner end thereof, the maximum diameter of the
base of the collet, that is to say the part towards the outer end,
must not exceed the minimum diameter of the aforementioned member
having the cam surface. One is thus led to a construction in which
the main body is formed in two parts. In one form of construction,
such as that shown for example in U.S. Pat. No 3,454,290, these two
parts can be threaded one on to the other so that they can be
separated by being unscrewed when it is required to obtain access
to the collet to enable a tube to be withdrawn. If the two parts of
the body are secured together after the collet has been assembled
in the cam surface member, then release of a tube from the coupling
can only be effected by ensuring that the collet protrudes
outwardly from the body. However this part of the collet, as
explained above, must not have any portion of greater diameter than
the minimum diameter of the cam surface member. In practice this
means that the end of the collet is a relatively thin cylinder, as
for example in the constructions of U.S. Pat. No. 3,653,689,
thereby raising problems in applying axial pressure to this collet
when a tube is to be released. It is possible, as shown in U.S.
Pat. No. 3,743,326, to swage the outer end of the collet radially
outwardly thereby increasing its diameter but this results in the
collet being permanently secured onto the member surrounding it, so
preventing dismantling of the assembly.
SUMMARY OF THE INVENTION
According to this invention, in a tube coupling of the kind having
a collet with resilient arms arranged to co-operate with a cam
surface constituted by a member surrounding the collet and having
an internal surface tapering in one axial direction engaging the
arms so that the fingers are forced inwardly by axial movement of
the collet in said one direction, the collet has its arms spaced
apart in the circumferential direction such that, in the absence of
any tube within the collet, the arms can move inwardly to permit of
the collet being withdrawn from said member by axial movement in
said one direction.
By adequately spacing the arms in this way so that they can deform
inwardly sufficiently to permit of withdrawal of the collet from
the member, it now becomes possible to insert the collet into this
member from the outer end thereof. This immediately leads to a
number of significant advantages. In the first place the body of
the tube coupling can be made as a unitary structure incorporating
the cam surface instead of having to be made in at least two parts
as heretofore. This obviously simplifies the construction. The
assembly of the coupling unit is simplified in that the collet can
readily be inserted from the outer end.
A further very important advantage however of this construction,
which arises because the collet can be inserted from the outer end,
is that there is now no restriction on the diameter of the outer
end of the collet. The collet therefore may extend radially
outwardly at the outer end to be larger than the bore in said
member, e.g. the collet may have a radially extending flange at the
outer end, that is to say the end remote from the arms. Such a
radial extension or flange facilitates the applying of
axially-inwards pressure when it is required to remove a tube from
the coupling. Moreover, the coupling can be locked by putting a
clip between such a flange and the outer surface of the body of the
coupling to prevent inward movement of the collet.
As will be apparent from the following description, this
construction in which the collet can be inserted into the coupling
from the outer end thereof furthermore greatly facilitates the
manufacture of the collet.
In one form of construction according to the invention, a tube
coupling comprises an outer member having an internal bore, a
collet fitting in said bore from one end thereof and a seal,
conveniently an O-ring seal, seated within said bore against a
shoulder therein which shoulder faces the end from which the collet
is inserted, the bore in said member, between the shoulder and the
end from which the collet is inserted having a tapered section
tapering from the larger diameter part enclosing the seal down to a
smaller diameter portion within which the collet is slidable, and
the collet including a portion of externally cylindrical form
slidable in the reduced diameter portion of the sleeve, from which
externally cylindrical portion there extends, in an axial
direction, three or more resilient arms for gripping a tube, said
arms having, on their outer faces, surface portions for engaging
the tapered part of said bore, said collet furthermore having a
cylindrical bore with inwardly extending projections at the ends of
said arms remote from the cylindrical portion of the collet which
inwardly extending portions have a sloping face on the surface of
those portions facing towards the outer end of the collet and bore,
the collet being so dimensioned that the collet may be forced into
the bore in said member by flexing of said arms to permit the ends
of the arms to move inwardly so that they can pass through the
reduced diameter portion of the bore, and the inwardly extending
projections on the collet arms being of such dimensions compared
with the diameter of the enlarged portion of the bore and the outer
surface of the collet arms that, when the collet is adjacent the
seal, a tube can be forced through the collet to bear against the
inwardly extending projections and, by reason of their slope, force
the collet arms apart so that the tube passes through the collet
and the seal to be resiliently gripped by the collet. With this
construction, any pull on the tube causes the collet to slide in
the bore. The engagement of the tapered surfaces of the bore and
collet causes the collet arms to be pressed more tightly onto the
tube thereby gripping the tube firmly against withdrawal. The tube
however can be released from the coupling by pressing the collet
into the bore whilst pulling on the tube. With the collet pressed
into the bore, the collet arms are in a position where they can
expand outwardly and hence the only grip on the tube is the
resilient grip due to the resilience of these arms. It is thus
possible to withdraw a tube if necessary although, in normal use, a
pull on the tube serves to tighten the grip on the tube.
The aforesaid member may form part of other equipment to which the
tube is to be coupled. For a coupling for coupling two tubes
together, said member may be constituted by a single sleeve with a
collet and O-ring inserted from each end. If the two tubes to be
coupled are of identical size, the coupling is symmetrical.
Obviously however couplings can be made for coupling tubes of
different sizes if so desired.
It will be seen that this coupling comprises essentially an outer
member, a collet and an O-ring and that the components can be
assembled together with the O-ring, because of its resilience,
being readily insertable into the bore and the collet then also
being insertable into the bore from the open end thereof. It is
thus possible if necessary to withdraw and replace a collet. This
is in contrast to many forms of coupling using collets in which the
collet has to be permanently retained within an outer member.
The bore in the aforesaid member preferably, beyond the O-ring
seal, has a cylindrical portion of suitable diameter to be a close
fit on the tube, this cylindrical portion terminating in a shoulder
forming an abutment for the end of the tube.
To facilitate insertion of the collet into the bore, preferably the
mouth of the bore has a tapered surface and the ends of the collet
arms have correspondingly sloped surfaces for engaging the tapered
mouth so that the collet arms are gradually forced inwardly as they
enter the mouth of the bore.
Variations in tube diameters may readily be accommodated by
interchangeable collets and O-rings. This is particulary convenient
when different size tubes for example metric or imperial size tubes
have to be connected to a common fitting.
It will be understood that, when reference is made to the outer
member, this includes any bored member suitably shaped internally.
It may be part of a valve or other fitting.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, illustrating one embodiment of the invention, shows a
sleeve and a collet in longitudinal section and separate from one
another;
FIG. 2 shows the sleeve and collet of FIG. 1 assembled
together;
FIG. 3 shows the coupling of FIG. 1 with a tube therein;
FIG. 4 is a view similar to FIG. 3 of another embodiment showing
the use of a clip to prevent inward movement of the collet;
FIG. 5 is a section along the line 5--5 of FIG. 4;
FIG. 6 illustrates a modification of the coupling of FIGS. 1 to
3;
FIGS. 7 and 8 illustrate one method of making a collet as used in
the construction of FIG. 6;
FIG. 9 illustrates a modification of the coupling of FIG. 6;
and
FIGS. 10 and 11 are sectional elevations illustrating a coupling
for joining two tubes together.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1, 2 and 3, there is shown a body member in the
form of a sleeve 10 which may be part of a valve or coupling insert
or other device. It is shown diagrammatically with a cylindrical
outer surface but, as will be apparent from the following
description, the outer surface is immaterial to the function of the
coupling and the bore within the sleeve may be formed in a device
of any shape. Considering the bore from the outer end, that is to
say the left-hand end of FIG. 1, it starts with a short convergent
section 11 forming a mouth leading to a cylindrical portion 12 at
the inner end of which there is a divergent portion 13 having, in
this particular embodiment, a straight divergent taper which leads
to an enlarged diameter portion 14. The end of the enlarged
diameter portion 14 is formed by a shoulder 15 extending inwardly
to a smaller diameter portion 16 which as explained later is of
just sufficient size to accommodate the tube with which the
coupling is to be used. The inner end of this portion 16 is
terminated with a further shoulder 17 to form a stop for the tube
when the tube is inserted, the bore continuing with a reduced
diameter portion 18 forming a fluid flow passage.
The collet 20 has at its outer end a flange 21. From this flange
there extends a cylindrical portion 22, the flange cylindrical
portion being internally of a size just sufficient to accommodate
the tube to be coupled and externally of a size to slide in the
cylindrical portion 12 of the sleeve. At the inner end of the
portion 22 the collet continues in the form of four axially
extending arms 23 separated by slots 24. Each arm includes a
reduced diameter portion 25 to permit flexing of the arm and, at
the end furthest into the bore, has an enlarged diameter portion 26
with an external taper surface 27 matching the aforementioned taper
of the divergent portion 13 in the bore of the tube. The collet is
formed so that the arms thereof, in their normal position, are as
shown in FIG. 1. The largest diameter portion occurs at 28 and,
beyond this, there is a short sloping outer surface 29 leading
towards the end of the collet which end has a surface 30 extending
radially inwardly and backwardly towards the flange end of the
collet. This sloping surface 30 leads down to a projecting portion
32 which, in the normal position of the collet arms as shown in
FIG. 1, lies radially inwardly of the bore of the cylindrical
portion 22 of the collet. From this projection 32, there is a
sloping surface on the arms leading radially outwardly and
backwardly towards the flange as shown at 33. This surface 33
extends to the cylindrical bore portion of the collet.
An O-ring seal 35 is inserted in the bore in the sleeve to rest
against the shoulder 15 therein. If, for any reason it is required
to remove this seal, this can readily be done with a hooked
tool.
The collet 20 is put in the sleeve 10 from the open end thereof.
The convergent inlet end 11 of the sleeve engages the sloping
surface 29 on the end of the collet arms forcing these collet arms
together. They flex at the portions 25 where they are of reduced
thickness and this permits the collet to be inserted through the
cylindrical portion 12 of the sleeve. The spacing between adjacent
arms has to be made sufficient to permit of adequate inward
deformation. When the collet arms have been passed through this
portion, they can expand outwardly as shown in FIG. 2. It will be
seen from this figure that the collet has a certain amount of play
in the sleeve, being able to slide axially therein. Inward movement
is limited by the collet bearing against the O-ring 35. On outward
movement, the tapered surfaces 27 of the collet arms engage the
tapered surface 13 of the bore of the sleeve. Removal of the collet
is possible by pulling on it so as to force the arms inwardly
together if it is necessary to dismantle the coupling.
To form a tube coupling, the collet and O-ring are assembled in the
bore as shown in FIG. 2 and a tube is inserted therein from the
open end of the collet in the direction indicated by the arrow X.
The tube is shown in FIG. 3 at 40. It will be seen that, as it is
inserted, it can be readily pressed through the greater part of the
length of the collet which has a smooth cylindrical bore. The end
of the tube will eventually bear against the surfaces 32 on the
ends of the collet arms and will force these arms outwardly as
shown in FIG. 3. The tube can then be forced on through the O-ring
to bear against the shoulder 17 in the sleeve. The tube is thus
resiliently gripped by the collet arms and is sealed in the
coupling by the O-ring seal. If there is any outward pull on the
tube, the tapered surfaces 27 of the collet arms engage the tapered
surface 13 of the bore of the sleeve so forcing the arms inwardly
to grip the tube more tightly. Thus the tube is held firmly against
withdrawal. It is possible however to release a tube, if required,
by holding the collet tightly in against the O-ring seal, thereby
holding the collet arms in a position where they can be forced
outwardly and then pulling on the tube to overcome the friction
grip due to the resilience of the collet arms.
FIGS. 4 and 5 illustrate how a spring clip 41 can be put between
the flange 21 and the outer end of the body member 10. The
insertion of such a clip prevents the collet being pushed into the
body member and hence prevents the tube being withdrawn. FIG. 4
also shows a step 36 between the surfaces 13 and 12. If the
coupling is to pass a high pressure fluid, pressure on the O-ring
35 may force the collet back but this step prevents the collet
being forced out of the sleeve 10.
In some cases, e.g. where the tube is a glass tube or where it is
the outer sheath of an electric cable, e.g. a mineral insulated
metal sheathed cable, it may be desirable to have a protective bush
around the tube made of elastomeric material which will grip the
tube firmly when the arms are pressed into the plastics material.
Such a construction is shown in FIG. 6 in which a bush 42 or rubber
or plastics elastomeric material is provided within a collet 43 to
hold a tube 44 within a body member 45. In this construction, the
collet may be of relatively thin material; whilst it may be
die-cast, conveniently, it is formed of strip material, as shown in
FIGS. 7 and 8. FIG. 7 shows flat strip material 46 in plan after
shaping to have indents 47 and four arms 48 while FIG. 8 is an end
view of the material before it is shaped into the collet 43.
In FIG. 6, there is shown a separate O-ring seal 49 between the
bush and the shoulder in the body member. The O-ring might be
located over the periphery of the bush. With an elastomeric bush
around the tube, it is possible, as shown in FIG. 9 to have one
piece bush and seal 50 for gripping a tube 51 and sealing it into a
body member 52.
Another way of forming a collet such as collet 43 of FIG. 6 is by
deep drawing from a circular metal blank and then piercing and
slotting to form the required arms.
FIGS. 10 and 11 illustrate a tube coupling for joining two tubes
55, 56. The coupling comprises an outer sleeve 57 containing an
O-ring seal 58 in a central groove 59. Two similar collets 60, 61
are located in the sleeve, one at each end, each having an
associated O-ring seal 62. These collets are similar to the collet
of FIGS. 1 to 3. To join the tubes 55, 56 together, the coupling is
first put over tube 55, as shown in FIG. 10. To do this, the collet
61 must be held inwardly, that is pushed to the left with respect
to the sleeve, so that the tube 55 can pass right through the
coupling. Tube 56 is then located in position and a force applied
to collet 60 so that this collet is held in the release position
enabling the coupling to slide back along tube 55, the tube 56
entering into collet 61.
* * * * *